Preparation of white oils and liquid paraffins



United States Patent 14 Claims. (61. 208-264) This invention relates to a process for the production of white oils and liquid paraffius.

White oils belong to a known class of oils which are used, according to the degree of refinement, as lubricating oils (for example in the precision engineering industry, as Watch oils and sewing machine oils), as cosmetic or pharmaceutical oils. They normally have a viscosity of between 16 and .+30 Saybolt.

Liquid paraflins are generally understood to mean those highly refined mineral oils whose characteristic properties are laid down in the different pharmacopoeias.

The production of these highly refined white oils is usually carried out from mineral oil distillates without or with solvent extraction, for example with furfural, followed by refining with considerable quantities of oleum, neutralisation and treatment with fullers earth.

This process possesses various disadvantages. Thus both the extraction and refining cause losses of 20 to 30% each of the oil and give corresponding quantities of byproducts (extract, acid tar), and utilisation or removal of which is diflicult and adds to the cost of the process. Total yields, reckoned on the distillate, are always less than 50 percent, depending upon the degree of refining.

This usual process is composed of four operating stages.

The solvent extraction is aimed at dissolving out the aromatic compounds which accounts for the greatest percentage, what is known as the solvent extract occurring as a byproduct. However, the latter still contains a considerable percentage of paraffinic and napthenic hydrocarbons (up to 50% of the amount of the extract), and these have to be regarded as a true loss of oil on account of the lower value of the extract, because at best they can be recovered by a further treatment of the extract which is uneconomical. Furthermore, the extracts suffer a deterioration in quality, for example during the extraction with furtural, as a result of oxidation and polymerisation.

The treatment with quantities of oleum of up to 50% by weight of the initial quantity of oil converts a considerable proportion of the oil (up to 50%) by chemical reactions (polymerisation, oxidation and sulphonation) into unsuable, bitumen-like black masses, known as acid tar, the disposal of which is expensive. Furthermore, the oleum treatment must be carried out in several stages in order to restrict the heat of reactionwhich can make a cooling process necessary-and this in turn means a larger container capacity or long duration of treatment (several days). The sulphonic acids formed during the oleum treatment and dissolved in the oil must be removed by an extraction process with alkaline ethyl alcohol, which is truly expensive as a result of the unavoidable losses of alcohol.

The concluding adsorptive treatment with fullers earth is aimed at removing the last traces of impurities. Here again oil losses occur, which amount to approximately 3,328,293 Patented June 27, 1967 the weight of earth used. Under certain circumstances this treatment has to be repeated and removal of consumed fullers earth is bound up with diifioulties and expense on account of its oil content.

The object of the present invention is a process which operates according to a completely different principle, very considerably reduces the extent of the technical drawbacks of the old process and consequently is also considerably more economical.

Unlike the usual process, in the process according to the present invention practically all the compounds contain-ed in the distillate are attained as usable products. Acid and fullers earth treatments are only necessary to a smail extent for the liquid paraflin only. The only waste material which occurs is sulphureted hydrogen which can easily be removed as a gas and which does not matter from the point of view of quantity.

According to the present invention a process for the production of white oils and liquid paraflins comprises hydrogenating a mineral oil distillate in a first stage, and separating the hydrogenated products in a second stage into parafiins, naphthenes and aromatics by adsorption on a solid adsorbent. The adsorptively separated fractions may if necessary be lightly treated with oleum and fullers earth in order to give final products having a desired quality.

The first stage of the process on which the invention is based, the hydrogenation of mineral oil distillates, is in itself known in various forms of execution. However, these known hydrogenation processes are to be regarded as independent treatment processes. The hydrogenation stage of the present invention represents a part of the total process and serves to pretreat the oil ready for the second part of the process. Its purpose is to convert strongly polar compounds such as for example sulphur, oxygen and nitrogen compounds and also olefins, which would rapidly and irreversibly make the adsorbent of the subsequent adsorption stage inelfective, into non-polar compounds which do not have a deleterious influence on the adsorbent. At the same time the hydrogenation brings about an increase in the parafiinic and napthenic fractions in the oil and consequently greater yields of end products.

The hydrogenated oil contains only paraflins, naphthenes and low-polar aromatics and is therefore suitable for use for the second stage of the process according to the invention, the adsorptive separation over solid adsorbent.

The adsorptive separation splits the hydrogenated product without any chemical conversions into paraflins, naphenes, and aromatics. The preferred adsorbent is silica gel.

The yields of White oils and liquid paraffin obtainable by the process of the present invention are considerably greater than in one of the process stages alone or one of the conventional processes. Even the combination of a mild hydrogenation with the adsorptive separation leads to increased yields.

The properties of the adsorption fractions are so good that only in the case of the production of liquid paraffin is it necessary to carry out a final treatment with oleu-m/ fullers earth.

The aromatic fraction occurs in greater purity with considerably lighter colour (ASTM 1-3), better colour stability and a considerably lower content of paraflins and naphthenes than is the case with solvent extractions. This means an increase in the value of the aromatic fraction as compared with the extracts from solvent extraction and a considerably higher yield of white oil.

The combination of hydrogenation and adsorption thus offers great advantages from the chemical, technical and economic points of view, which are unexpected and which cannot be achieved either by using these processes by themselves or by combination with other conventional processes, such as for example oleum refining or solvent extraction. In order to use these advantages to the full extent it is expedient to maintain certain process conditions for both stages of the process:

The hydrogenation is advantageously carried out at temperatures between 250 and 400 C., preferably 320 to 380 C.

The pressure may be within the range from 5 to 150 kg./cm. but is preferably from 30 to 90 kg./cm.

The throughput speed of the oil can amount to 0.1 to 5 vols. of oil per vol. of catalyst per hour, and that of the hydrogen can be from 5 to 500 vols. of hydrogen per vol. of oil. The hydrogen can be fed in on a once-through basis or it can be circulated.

Suitable catalysts should be sulphur-resistant and may comprise oxides and sulphides of the metals of the 6th group and the 8th group of the Periodic Table, such as for example iron, cobalt, nickel, molybdennm and tungsten on suitable refractory inorganic oxide supports. A catalyst of the composition NiS.WS .Al O is particularly suitable.

The hydrogenation product is freed from dissolved sulphuretted hydrogen, ammonia and water by stripping with the usual stripping agents, for example nitrogen or steam in the usual apparatus at elevated temperatures, whereupon it is ready for charging to the adsorption stage.

For the adsorptive separation the oil may be fed into a column with an adsorbent, preferably in a proportion of 0.1 to 0.6 kgs. of oil per kg. of adsorbent. According to the content of paraffinic compounds in the oil, 100 to 200% of a low-molecular aliphatic hydrocarbon, for example pentane, is pumped through the column, the paraffins and naphthenes being eluted successively. Instead of pentane it is also suitable to use, for example, butane, hexane and heptane. In the case of butane it is necessary to operate under elevated pressure because of its low boiling point.

The aromatics are then eluted with 100 to 400% of a low-molecular aromatic hydrocarbon, for example benzene, after which the adsorbent is once again ready for the next adsorption operation. Instead of benzene it is also possible to use its homologues toluene and xylene.

A sharpening of the separation effect is achieved if the layer formed by the elution agent for the aromatics is displaced by an interim run-through of eluting agent for the aliphatics.

In the case of highly viscous oils it is necessary to dilute the oils with low-molecular hydrocarbons, especially aliphatic hydrocarbons such as for example pentane. The elution operations can also be carried. out at elevated temperatures up to the boiling point of the eluting agent.

The following adsorption conditions may be selected.

0.1 to 0.8 dm. oil/dm. Column cross section per minute. Adsorbent Highly active silica gel. Particle size of adsorbent 0.1 to 1 mm. Temperature 20 to 60 C.

The degree of separation differs according to the number of fractions withdrawn per unit volume of the column. The limits of the different fractions can be determined by means of indices of refraction and ultraviolet fluorescence. The paraflinic fraction constitutes the basis for liquid paraffin and only requires a final treatment with 4% oleum. The naphthenic fraction occurs as white oil and requires no further treatment.

Besides silica gel it is also possible to use active forms of aluminium oxide as adsorbents. The adsorption and desorption equilibria naturally depend greatly upon the adsorbent and are different in the case of A1 0 The process according to the invention is suitable for the treatment of all mineral oil fractions.

EXAMPLE 1 A de-waxed Middle East spindle oil distillate is hydrogenated by means of a catalyst consisting of sulphides, and oxides of the 8th Sub-Group of the Periodic Table on A1 0 as support under the following conditions:

Temperature 360 C.

Pressure kg./crn.

Throughput speed 0.1 vol. oil/vol. catalyst per hour.

Gas rate 175 vols. residual gas per vol. of oil.

The hydrogenation product is freed from sulphuretted hydrogen, ammonia and water with nitrogen at C.

The product which has been prepared in this way is subjected to a silica gel adsorption under the following conditions:

The following fractions are collected separately:

(1) Pentane eluate with indices of refraction n 1.4688

This fraction consists of practically pure paraffins and occurs in a quantity of a maximum of 28% of the charge of hydrogenation products. After a finishing with 4% oleum and 3% fullers earth a liquid paraifin is obtained in a 90% yield, which corresponds to the specifications required by the various pharmacopoeias and furthermore shows the following characteristics:

Colour +30 Saybolt.

WOMA lustre Free.

Viscosity (20 C.) 32.2 cst.

Specific gravity (15 C.) 0.858.

Hot acid test 1.8 yellow-0.7 red Lovibond.

UV fluorescence Neg.

(2) Pentane eluate with indices of refraction This mixture contains paraffins with small polar radicals in the molecule and also naphthenes. It immediately follows the the fraction 1 in the elution with pentane. It

constitutes a light white oil andrequires no further processing:

Colour Saybolt +30 WOMA lustre +1 Viscosity (20 C.) cst 32.8 Specific gravity (15 C.) 0.865 Cold acid test Ostwald +3 (3) Benzene eluate The benzene eluate contains only aromatic compounds. The oil remaining after distilling off the benzene has the following characteristics:

Colour, ASTM l Viscosity (20 C.) cst 48.5 Specific gravity (15 C.) 0.9224 SK index percent 2.8 Furfural index do 7.5 Sulphur ..do 0.16

Yields and quantities of oleum required, reckoned on the EXAMPLE 2 If the entane eluate in Example 1 is collected in one fraction and if one does away with the subdivision into parafiins and naphthenes, which is technically the simplest, by operating according to the process conditions of Example 1 one obtains a White oil to the extent of 70% oleum and 3% fullers earth to give the following white oil with a 95% yield:

Colour Saybolt +30 WOMA lustre +1 Viscosity (20 C.) cst 39 Specific gravity C.) 0.870 Cold acid test Ostwald 6 (3) Benzene eluate After distilling otf the benzene a product is obtained representing 46% of the hydrogenation product and possessing the following data:

of the hydrogenation product, with the following data: 15 Colour "ASTM" 35 COlOur Saybolt +30 Viscosity C.) cst-- 8O WOMA lustre 1 Specific gravity (15 C.) 0.975 Viscosity (20 C.) cst 32.6 SK index 29 Specific gravity (15 C.) 0.864 F-urfural index 23 Cold acid test OstWald 3 20 Sulphur percent 3.15 UV fluorescence pos.

Total yields and quantities of oleum required, reckoned on Yields, reckoned on the distillate: Percent the distillate. percent White 0il(Wifl1011tO1e11m) 69 Liquid araffin 1 g% oleum) 22 Light-coloured aromatics (colour 1 ASTM) 29 White on (12% oleum) 28 Hydrogenation loss 2 Aromatics 5 By refining this white oil with 4 7.5% oleum and 3% Hy r g n i and r g losses 5 fullers earth a liquid paraflin is obtained in a 91% yield, complying with the specifications of the various pharmacopoeias. It is characterised by the following additional data:

Colour +30 Say bolt.

WOMA lustre Free.

Viscosity (20 C.) 32 cst.

Specific gravity (15 C.) 0.862.

Hot acid test 2.1 yellow-1.0 red Lovibond. UV fluorescence Neg.

Yields, reckoned on the distillate: Percent 1. Liquid parafiin (approx. 21% oleum) 62 Light-coloured aromatics (colour 1 ASTM) 29 Hydrogenation and refining losses 9 EXAMPLE 3 A de-waxed Middle East spindle oil distillate was hydrogenated under the following conditions by means of a catalyst which contains in addition to the oxides of cobalt and nickel also iron oxide and aluminium oxide as support:

Temperature 350 C. Pressure 40 k-g./cm.

Throughput speed 0.6 v. oil/v. catalyst/ hr.

Gas rate 100 v. residual gas/v. oil.

The product obtained under these hydrogenation conditions was adsorptively separated as stated in Example 1.

(l) Pentane eluate with refraction indices n l.4678

This fraction amounts to 24% of the hydrogenation (2) Pentane eluate with refracitve indices n =1.4688-1.479

This fraction which occurs in a quantity of 30% of the hydrogenation product can be refined with 4% I claim:

1. A process for the production of white oils and liquid parafiins in high yield from a mineral oil distillate having aromatics, naphthenes and paraifins therein which comprises subjecting the mineral oil distillate to a catalytic hydrogenation operation at a temperature of from 250 to 400 C., under a pressure of from 5 to 150 kg./cm. at a distillate throughput speed of from 0.1 to 5 vols, of oil per vol. of catalyst per hour and a hydrogen throughput of from 5 to 500 vols. of hydrogen per vol. of oil, the hydrogenation catalyst being sulphur resistant and being a material selected from the group consisting of oxides and sulphides of the metals of the 6th group and the 8th group of the Periodic Table on a refractory oxide support, said hydrogenating operation converting strongly polar compounds of said distillate into non-polar compounds and increasing the naphthenic and paraffinic content of said distillate, feeding the hydrogenated distillate and a solid adsorbent material selected from the group consisting of silica gel and active forms of aluminum oxide into an adsorption column, passing an eluting agent through said adsorption column to successively elute paraifinic and naphthenic hydrocarbons therefrom, and recovering a paraflinic hydrocarbon fraction as a basis for obtaining liquid paraflin and a naphthenic hydrocarbon fraction as white oil.

2. A process as claimed in claim 1 wherein the hydrogenated distillate is adsorptively separated into said parafiinic and naphthenic fractions on the one hand and an aromatic fraction on the other.

3. A process as claimed in claim 1 wherein the adsorptively separated paraffin fractions is lightly treated with up to 4% oleum and up to 3% fullers earth.

4. A process as claimed in claim 1 wherein the hydrogenation is carried out at a temperature of from 320 to 380 C., and under a pressure of from 30 to kg./cm.

5. A process as claimed in claim 1 wherein the hydro genation is catalysed by a sulphur-resistant catalyst comprising components selected from the group consisting of oxides and iron, cobalt, nickel, molybdenum and tungsten, on alumina as a support.

6. A process as claimed in claim 1 wherein the hydrogenated product, before being separated in said second stage, is stripped at elevated temperature with a stripping agent selected from the group consisting of nitrogen and steam.

7. A process as claimed in claim 1 wherein the parafiinic and naphthenic hydrocarbons are eluted successively from the adsorbent with a low-molecular aliphatic hydrocarbon.

8. A process as claimed in claim 7, wherein pentane is used as the eluting agent.

9. A process as claimed in claim 1 wherein the aromatic hydrocarbons are eluted With a low-molecular hydrocarbon.

10. A process as claimed in claim 7 wherein benzene is used as the eluting agent.

11. A process as claimed in claim 1 wherein the elu tion is carried out at temperatures up to the boiling point of the eluting agent.

12. A process as claimed in claim 1 wherein the elution of the aromatics, the aromatic solvent is displaced from the adsorbent by a low-molecular aliphatic hydrocarbon.

13. A process as claimed in claim 1 wherein in the event of the occurrence of more highly viscous hydrogenation products, these are diluted With a low-molecw lar hydrocarbon before the selective adsorption.

14. A process as claimed in claim 1 characterised by the use of silica gel as the adsorbent.

References Cited UNlTED STATES PATENTS DELBERT E. GANTZ, Primary Examiner.

SAMUEL P. JONES, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,328 ,293 June 27 1967 Horst Brenken It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 30, for "and utilisation" read the utilisation line 52, for "unsuable" read unusable column 2 line 2 for "and removal" read and the removal line 15 f "sulphureted" read sulphuretted column 3, line 24, for "group", each occurrence read Group column 5 line 9 0 "entane" read pentane column 6, line 35, for "vols," read vols. lines 40 and 41, for "group", each occurrence, read Group--; line 59, for "fractions" read fraction line 67, for "iron," read sulphides of iron, column 7, line 13 for "wherein the elution" read wherein after the elution Signed and sealed this 1st day of October 1968. (SEAL) Attest: Edward M. Fletcher, Jr. EDWARD 1- BRENNER Attesting Officer Commissioner of Patents 

1. A PROCESS FOR THE PRODUCTION OF WHITE OILS AND LIQUID PARAFFINS IN HIGH YIELD FROM A MINERAL OIL DISTILLATE HAVING AROMATICS, NAPHTENES AND PARAFFINS THEREIN WHICH COMPRISES SUBJECTING THE MINERAL OIL DISTILLATE TO A CATALYTIC HYDROGENATION OPERATION AT A TEMPERATURE OF FROM 250* TO 400*C., UNDER A PRESSURE OF FROM 5 TO 150 KG./CM.2, AT A DISTILLATE THROUGHPUT SPEED OF FROM 0.1 TO 5 VOLS, OF OIL PER VOL. OF CATALYST PER HOUR AND A HYDROGEN THROUGHPUT OF FROM 5 TO 500 VOLS. OF HYDROGEN PER VOL. OF OIL, THE HYDROGENATION CATALYST BEING SULPHUR RESISTANT AND BEING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF OXIDES AND SULPHIDES OF THE METALS OF THE 6TH GROUP AND THE 8TH GROUP OF THE PERIODIC TABLE ON A REFRACTORY OXIDE SUPPORT, SAID HYDROGENATING OPERATION CONVERTING STRONGLY POLAR COMPOUNDS OF SAID DISTILLATE INTO NON-POLAR COMPOUNDS AND INCREASING THE NAPHTHENIC AND PARAFFINIC CONTENT OF SAID DISTILLATE, FEEDING THE HYDROGENATED DISTILLATE AND A SOLID ADSORBENT MATERIAL SELECTED FROM THE GROUP CONSISTING OF SILICA GEL AND ACTIVE FORMS OF ALUMINUM OXIDE INTO AN ADSORPTION COLUMN, PASSING AN ELUTING AGENT THROUGH SAID ADSORPTION COLUMN TO SUCCESSIVELY ELUTE PARAFFINIC AND NAPHTHENIC HYDROCARBONS THEREFROM, AND RECOVERING A PARAFFINIC HYDROCARBON FRACTION AS A BASIS FOR OBTAINING LIQUID PARAFFIN AND A NAPHTHENIC HYDROCARBON FRACTION AS WHITE OIL. 